<!-- 页面标题显示学习 -->


<!DOCTYPE html>

<html lang="en">

<head>
	<meta charset="UTF-8" />
	<title>Jack</title>

</head>

<body>
	<h1>标题1</h1>
	<h2 lang="ch">标题2</h2>
	<h3>标题3</h3>

</body>